This was a reply to my search for a adapter plate in the PARTS WANTED FORUM:
(Quote)
The factory Powerglides in the '60-'66 Chevy trucks are the same, whether attached to a factory V8 (283 or 327) or a factory straight six (230, 235, 250 or 292). I don't think you need an adapter plate to mate a Powerglide to a sbc.

Does any body know if this is TRUE, Has anybody done this installation? I would like to find out before I start buying Adapter Plates, new Tranys, etc.

Thanks,
62MUCH